Catheter device

ABSTRACT

The catheter device comprises a drive shaft connected to a motor, and a rotor mounted on the drive shaft at the distal end section. The rotor has a frame structure which is formed by a screw-like boundary frame and rotor struts extending radially inwards from the boundary frame. The rotor struts are fastened to the drive shaft by their ends opposite the boundary frame. Between the boundary frame and the drive shaft extends an elastic covering. The frame structure is made of an elastic material such that, after forced compression, the rotor unfolds automatically.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/862,752 filed on Apr. 15, 2013, now U.S. Pat.No. 9,072,825 which in turn is a divisional application of U.S. patentapplication Ser. No. 12/210,435, filed on Sep. 15, 2008, now U.S. Pat.No. 8,439,859 which in turn claims priority to U.S. ProvisionalApplication No. 60/978,249 filed in the United States Patent andTrademark Office on Oct. 8, 2007, the contents of all which are herebyincorporated by reference herein for all purposes.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a catheter device which is a miniaturised pump.

Related Art

Implantable blood pumps are used increasingly in the treatment ofpatients with serous heart conditions. Such blood pumps have so far beenprovided mainly for long-term use. However, blood pumps are also beingdeveloped which are designed for short-term support for the heart andmay be inserted by minimally invasive means. Here the medical objectivesare stress-relief for and recovery of the heart, or to provide bridginguntil a possible heart transplant. The range of application of suchpumps depends on the one hand on the simplicity of inserting them intothe body, and on the other hand on the feasible technical properties, inparticular the reliable operating life of the available pump systemswhich may be obtained. Ideally it should be possible to insert such ablood pump for short-term treatment by percutaneous-intravascular meanswithout any surgical intervention.

In cardiogenic shock, the ejection performance of the left ventricle isconsiderably reduced. The reduced coronary supply can lead toirreversible heart failure. Through the use of a temporaryleft-ventricular support system, the pump function of the left ventricleshould be partly or largely taken over and the coronary supply improved.In heart operations such a system may be used for both left and rightventricles and may replace a heart-lung machine.

A percutaneous-intravascular system which has to date been of clinicalimportance is the intra-aortal balloon pump (IABP). The intra-aortalballoon pump or intra-aortal counter-pulsation is a mechanical system,also used to support the pumping performance of the heart in patientswith cardiogenic shock. This involves a catheter with a cylindricalplastic balloon being pushed ahead via the groin into the thoracic aorta(aorta thoracalis), so that the balloon lies below the outlet of theleft clavicular artery (arteria subclavia sinistra). There the balloonis blown is inflated rhythmically by an external pump with every heartaction in diastole with 30-40 cm³ helium and deflated in systole. Inthis way the balloon pump improves the blood supply to the heart muscleand also that of all other organs. The obtainable haemodynamicimprovement is however very limited since, on account of theconstruction principle of the IABP, no active blood delivery takesplace. Through counter-pulsation only the aorta is closed below the leftventricle in the rhythm of the heartbeat, so that the blood stilldischarged by the heart is pressed back and redistributed, also in thecoronaries. There is no increase in blood flow.

A known transfemoral implantable micro axial pump, “Hemopump™” of thecompany Medtronic Inc., USA, represents after experimental andpreliminary clinical testing a promising concept for effecting adequaterelief of systemic heart strain. The intake nozzle of the pump is placedin the left ventricle retrogressively via the aortic valve. The pumprotor is located at the end of a cannula in the upper aorta descendensand is driven by an external motor. The disadvantage of the system isthat the transfemoral implantation, due to the large diameter of therotor, is possible only through an operation involving a femoralarteriotomy and if necessary by a graft coupling.

WO 99/44651 discloses an axial pump which may be introduced via theblood vessel system of a patient. The axial pump has a flexible,compressible tube which forms the pump housing. In the tube is aradially compressible rotor. The drive shaft of the rotor runs through acatheter. Together with the tube and the rotor, the catheter may bedrawn into a cover hose. The radial compressibility of the componentsmakes it possible to realise a small puncture diameter suitable forpercutaneous implantation by the Seldinger technique. Through theunfolding in the heart vessel system, a relatively large pump diameterof 10 to 14 mm may be provided. This reduces the rotor speed andtherefore the mechanical stress on the components.

Described in U.S. Pat. No. 4,753,221 is a catheter with an integratedblood pump which has folding blades. The blood pump is an axial pumpprovided with a balloon at its end. The balloon can be pumped up tounfold the pump jacket and to close the flow path leading past the pump,so fixing the pump in the blood vessel. In a further embodiment it isprovided that a cup-shaped end of the catheter is arranged in a tubularguide catheter which is then withdrawn so as to unfold the cup-shapedend.

DE 10 059 714 C1 discloses an intravascular pump. The pump has a drivesection and a pump section which are so small in diameter that they canbe pushed through a blood vessel. A flexible cannula adjoins the pumpsection. To reduce flow resistance, the cannula may be expanded to adiameter which exceeds that of the drive section and pump sectionrespectively. So that the pump may be introduced into the body by theSeldinger technique involving punctures in the blood vessel, the cannulais constricted, in which state it has a smaller diameter. In the bloodvessel it is expanded so as to offer less flow resistance to the bloodto be pumped.

Described in JP 4126158 and EP 0 445 782 A1 respectively is anartificial heart for implantation in the body. The artificial heart hasa pump section and a drive section for driving the pump section. Thepump section is relatively small and serves to accommodate an axial flowpump in the form of a screw pump. Different types of screw pump areprovided.

Described in EP 0 364 293 A2 is a catheter with integral blood pump. Aflexible edge extends over a tubular section of the catheter andcontacts the wall of the aorta, ensuring by this means that all theblood within the aorta flows through the pump. In addition the flexible,expandable edge provides clearance between the pump and the aorticvalve.

SUMMARY OF THE INVENTION

The present invention provides for a blood pump to support the heart,and which may be inserted through the femoral artery bypercutaneous-intravascular means without the need for surgicalintervention.

The catheter device comprises a drive shaft connected to a motor, and arotor mounted on the drive shaft at the distal end section. The rotorhas a frame structure which is formed by a screw-like boundary frame androtor struts extending radially inwards from the boundary frame. Therotor struts are fastened to the drive shaft by their ends opposite theboundary frame. Between the boundary frame and the drive shaft extendsan elastic covering. The frame structure is made of an elastic materialsuch that, after forced compression, the rotor unfolds automatically.

Due to the frame structure of the rotor with its boundary frame androtor struts, the rotor is very stable but still capable of folding andof being compressed to a diameter virtually as small as may be desired.Due to the fact that, in principle, the rotor may be virtually as longas desired in the axial and radial directions, it may be optimised formaximum pump performance, depending on the space available. It istherefore possible to optimise pump performance for each application.

The rotor is so compressible that it may be introduced into the body,using a puncture needle, through a puncture with a diameter ofapproximately 9 french (approx. 3 mm). The automatic unfolding of therotor makes possible a rotor diameter which is many times greater thanthe diameter of the rotor in the compressed state. By this means a highpump performance is obtained.

Through the scaffolding-like structure of the boundary frame and rotorstruts, the rotor has great strength, enabling it to operate at highspeeds without becoming unbalanced. A prototype of this catheter devicewas operated over several hours to pump a fluid at a speed of around32,000 rpm. The rotor has a diameter of around 18 french (ca. 6 mm) andwas designed so as to obtain a pressure difference of approximately 120mmHg. This is an exceptional performance for such a miniaturised pump. Adistinct advance in reliability and operating life was also achieved bythis catheter device.

The frame structure of the pivot axis is preferably made from a memorymaterial such as nitinol. During compression, the rotor may be broughtto a temperature at which the memory material becomes soft. A rotor madeof nitinol is compressed for example at a temperature of around 0° C. Onheating, the memory material again becomes rigid and unfolds. As a ruleit is not possible to compress the rotor again without damage unless itis first cooled down.

The elastic covering between boundary frame and drive shaft ispreferably made of a polymer coating, e.g. polyurethane (PU),polyethylene (PE), polypropylene (PP), silicone or parylene.

Expediently the rotor is surrounded by a tubular pump section of a pumphousing. The pump housing is formed by a mesh, the openings of which areclosed by an elastic covering, at least in the area of the pump section.Such a pump housing may be made with a small clearance gap from therotor, resulting in optimal flow conditions and the chance for furtheroptimisation of pump performance.

The mesh of the pump housing is preferably made of a memory materialwhich can be compressed together with the rotor. The pump housingprotects the rotor from external influences.

Other features and advantages of the invention will be apparent from thefollowing detailed description, drawings and claims

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a perspective view of a catheter device according to theinvention,

FIG. 2 shows an exploded drawing of a catheter device according to theinvention.

FIG. 3 shows a body cap of the catheter device shown cut away at theside.

FIG. 4 shows a distal catheter body element of the catheter device in acut-away side view.

FIG. 5 shows a connection bush of the catheter device in a cut-away sideview.

FIG. 6 shows a pump of the catheter device with support in a cut-awayside view.

FIG. 7A shows a section along the line A-A through the distal connectionbush of the catheter device of FIG. 6.

FIG. 7B shows a section along the line B-B through the proximalconnection bush of the catheter device of FIG. 6.

FIG. 8 shows a mesh structure of a pump housing of the catheter device.

FIG. 9 shows a detail of the mesh structure of the pump housing of thecatheter device.

FIG. 10 shows a drive shaft with guide spiral and shaft protector of thecatheter device.

FIG. 11A shows a frame structure of a rotor of a pump of the catheterdevice.

FIG. 11B shows a further frame structure of the rotor of the pump of thecatheter device.

FIG. 12 shows the rotor according to the invention of the pump of thecatheter device in a perspective view.

FIG. 13 shows an outlet hose of the catheter device in a perspectiveview.

FIG. 14 shows a clutch according to the invention with clutch housingand motor of the catheter device in a perspective view.

FIG. 15 shows the clutch according to the invention with the clutchhousing of the catheter device in a perspective view.

FIG. 16 shows the clutch housing of the catheter device in a perspectiveview.

FIG. 17 shows a square rod of the clutch of the catheter device in aside view.

FIG. 18 shows a clutch element of the clutch of the catheter device in aside view.

FIG. 19 shows a terminating disc of the clutch of the catheter device ina side view.

FIG. 20 shows a ball head bearing ball of the clutch of the catheterdevice in a side view.

FIG. 21 shows a centering pin of the clutch of the catheter device in aside view.

FIG. 22 shows a motor mounting of the catheter device in a side view.

FIG. 23 shows a top view of the clutch element with the square rodcontained within it.

FIG. 24 shows the catheter device positioned in the body.

FIG. 25 shows an alternative embodiment of the catheter device inschematic form.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a catheter device 1. The catheter device 1 according to theinvention represents a pump. The catheter device 1 has a pump head 3 ata distal end 2.

The pump head 3 has a rotor 3.2, for pumping a medium in the flowdirection 5, which is connected to a drive shaft 4. The flow direction 5is from the distal end 2 to a proximal end 6. Located at the proximalend 6 away from the pump head 3 is a motor 7. The drive shaft 4 isencompassed by a catheter body 8 and connected non-positively by meansof a clutch 9 to the motor 7.

First of all the pump head 3 will be explained in more detail below. Thepump head 3 comprises a body cap 10 at the distal end, the rotor 3.2mounted on the drive shaft 4, a pump housing 3.1 and an outlet hose 18.

The body cap 10 is formed by a ball 10.1 with an attached cylindricalsection 10.2. The body cap 10 is made for example of stainless steel(FIG. 2, FIG. 3). The body cap 10 could be made of polyethylene PE,polypropylene PP, polyether etherketone PEEK, polyvinyl chloride PVC,Teflon PTFE, acrylic glass, epoxy resin, polyurethane PU, carbon fibre,coated materials, composite materials, PEBAX, or a polyether blockamide. In principle all haemo-compatible materials are suitable, sincethere is only minimal mechanical loading on this component.

The diameter of the ball 10.1 is roughly 3.2 mm, shown in FIG. 3. Thecylindrical section 10.2 is around 5.5 mm long and has a diameter ofapproximately 2.2 mm. The overall length of the body cap is roughly 7.0mm.

At its distal end, in the area of connection to the ball 10.1, thecylindrical section 10.2 has a through bore 10.3 running at right-anglesto the flow direction 5. The cylindrical section 10.2 also has an axialbore 10.4 which extends from the proximal end of the cylindrical section10.2 to the ball 10.1, thereby forming a communicating passage from thethrough bore 10.3 to the proximal end of the body cap 10. A step 10.5 isformed in the area of the axial bore 10.4, so that the latter is widenedtowards the proximal end.

The through bore 10.3 on the one hand avoids the creation of a blindhole in the body cap, while on the other hand permitting the attachmentof a thread, which is helpful in compressing the pump head 3.

Instead of the ball 10.1 of the body cap 10, a pigtail, a spiral, ameandering wire with a spherical tip, or an atraumatic fibre bundle mayalso be provided. The body cap is preferred owing to its small size.

The tip of the body cap 10 is an atraumatic ball to protect the heartmuscle (endocardium). Via the body cap 10, the pump head 3 may besupported on the wall of the heart.

A tubular or hose-like distal catheter body element 8.1 is introducedfrom the proximal end into the body cap 10 up to the step. The distalcatheter body element 8.1 is fixed in the axial bore 10.4 with anaccurate fit (FIG. 4). The distal catheter body element 8.1 is made ofpolyurethane or another suitable material, in particular an elastic,plastic material (e.g. PE, PVC, Teflon, elastomer). The distal end ofthe distal catheter body element 8.1 is connected to the body cap 10.The connection may be in the form of a bonded joint using for examplecyanacrylate adhesive, or may involve a welded, clamped or shrink-onconnection. These connection means are suitable in principle forconnecting a catheter body element to another, in particular a rigidone. In the description below, therefore, this will not be explained foreach individual connection point.

The distal catheter body element 8.1 forms a straight but very flexibleconnection between the body cap 10 and the pump housing 3.1. Thestraight connection creates a coaxial alignment of all the parts withinit (drive shaft, shaft protector, housing, connection bush).

In combination with the body cap 10, the distal catheter body element8.1 serves as a positioning aid when the pump head 3 is inserted into avessel or the heart.

In the present embodiment the catheter body element 8.1 has a length ofapproximately 25 mm, an outside diameter of around 1.9 mm and an insidediameter of around 1.3 mm.

Provided at the proximal end of the distal catheter body element 8.1 isa distal tubular connection bush 12.1 (FIG. 5, FIG. 6). The distalconnection bush 12.1 has a greater diameter in the distal area than inthe proximal area. In the distal area of the connection bush 12.1, theproximal end of the distal catheter body element 8.1 is held with a goodfit and fixed in place. Accommodated in the proximal area of the distalconnection bush 12.1 is a distal connection section 3.1.1 of the pumphousing 3.1. The distal connection section 3.1.1 of the pump housing 3.1is connected to the distal connection bush 12.1 and the proximal end ofthe distal catheter body element 8.1 (FIG. 7a , FIG. 7b ).

The distal connection bush 12.1 has a length of around 5 mm and anoutside diameter of approximately 2.2 mm. In the distal area, thediameter is roughly 2 mm and in the proximal area it is around 1.5 mm.The shorter the connection bush, the less the reinforcement which itprovides.

The distal and a similarly designed proximal connection bush 12.1, 12.2are made for example of stainless steel, copper, brass, titanium oranother suitable metal, of polyethylene (PE), polypropylene (PP), Teflon(PTFE), PEBAX, a polyether block amide or another suitable material.

The expandable or compressible pump housing 3.1 is a tubular meshstructure 3.1.6 of nitinol or another suitable memory alloy or anothermemory material, e.g. plastic, ferrous alloy, copper alloy. The pumphousing 3.1 is divided into five sections from the distal to theproximal end (FIG. 8). The first distal section is a tubular distalconnection section 3.1.1. A second section is an intake section 3.1.2widening conically in the flow direction 5. Next to the intake section3.1.2 is a pump section 3.1.3. The tubular pump section 3.1.3 holds therotor 3.2. In the expanded state, the inside diameter of the pumpsection 3.1.3 is around 6.15 mm. An outlet section 3.1.4 narrowsconically in the flow direction 5 and forms the connection between thepump section 3.1.3 and a proximal connection section 3.1.5. The proximalconnection section 3.1.5 is, like the distal connection section 3.1.1,tubular with a smaller diameter than the pump section 3.1.3. The pumphousing 3.1 may be so compressed that it does not exceed a maximumdiameter of less than 3 mm over its whole length.

Between the mesh struts, the mesh structure 3.1.6 of the pump housing3.1 has apertures 3.1.7 (FIG. 8, FIG. 9). The apertures are in the formof polygons 3.1.7, which in the present embodiment are rhombuses. In thepump section 3.1.3, small rhombuses 3.1.7.1 are provided. In thetransition zones from the pump section 3.1.3 to the intake section 3.1.2and the outlet section 3.1.4 of the tubular mesh structure 3.1.6, thesmall rhombuses 3.1.7.1 are combined step by step to form increasinglylarger rhombuses. Adjacent to a small rhombus is a larger rhombus withtwice the edge length. This doubling of edge length is repeated untilthe apertures reach the desired size. Provided in the intake section3.1.2 and in the outlet section 3.1.4 are large rhombuses 3.1.7.2 whichhave roughly four times the edge length of the small rhombuses 3.1.7.1.In the transition zones from the intake section 3.1.2 and the outletsection 3.1.4 to the distal and proximal connection sections 3.1.1,3.1.5 of the tubular mesh structure 3.1.6, the large rhombuses 3.1.7.2are turned into smaller rhombuses. In the distal and proximal connectionsections, medium-sized rhombuses 3.1.7.3 are provided which haveapproximately double the edge length of the small rhombuses 3.1.7.1(FIG. 9). The layout of the apertures 3.1.7 and the number of increasesin size may be as desired. In the transition from smaller to largerrhombuses the width of the mesh struts is increased. In this way thestrength of the mesh struts is kept roughly the same, and even increasedtowards the larger rhombuses.

The mesh structure 3.1.6 of the pump housing 3.1 is covered in the pumpsection 3.1.3 by a PU covering 3.1.8, which provides a liquid-proof sealof the mesh apertures.

This covering and the sealing of the mesh structure 3.1.6 may also beprovided by a PU hose fitted on to the outer or inner surface.

Other coverings than PU may also be used, e.g. PE, PP, silicone orparylene, so long as the mechanical and geometrical requirements aremet.

Through the selection of individual apertures 3.1.7.1, in particular themedium- and larger-sized apertures 3.1.7.3, 3.1.7.2, which are notcoated, the performance parameters including blood damage from the pump,may be controlled in a targeted manner.

The polygonal structure and the special finish of the PU covering resultin the pump housing 3.1 having an approximately round cross-section. Incombination with the round rotor 3.2, this leads to very small gapsbetween the rotor 3.2 and pump housing 3.1. This leads to comparativelylow blood damage, low leakage rates and high efficiency. The meshstructure 3.1.6 provides very good radial and axial stability togetherwith very good axial compression and expansion properties. The specialstructure makes possible very easy adaptation of length and diameter toperformance requirements.

The proximal connection section 3.1.5 of the pump housing 3.1 is held inand connected to the proximal connection bush 12.2. In the proximalconnection bush 12.2, as in the distal connection bush 12.1, a hose-likeproximal catheter body piece 8.2 is located and connected to it (FIG. 7a, FIG. 7b ). The same types of connection as already described above maybe provided.

Arranged axially within the distal and the proximal catheter bodyelement 8.1, 8.2 are a distal shaft protector 13.1 and a proximal shaftprotector 13.2 (FIG. 6). The distal and proximal shaft protectors 13.1,13.2 are in the form of hose made of PU or one of the other materialsalready referred to above.

The distal shaft protector 13.1 extends in the flow direction 5 fromshortly before the distal connection bush 12.1 to the distal end of thepump section 3.1.3 of the pump housing 3.1, i.e. as far as the rotor3.2. The proximal shaft protector 13.2 extends from the proximal end ofthe rotor 3.2 until shortly after the proximal end of the distalconnection bush 12.1.

In the two areas in which they lie within the distal and the proximalconnection bushes 12.1, 12.2 and the distal and proximal catheter bodyelements 8.1, 8.2 respectively, the distal and proximal shaft protectors13.1, 13.2 are joined to these former components.

Together with the components mounted within them (shaft protector, pumphousing, catheter body), the two connection bushes 12.1, 12.2 form abearing section for the drive shaft 4. The connection bushes 12.1, 12.2ensure the axial centricity of the drive shaft 4 in particular in thepump housing 3.1.

The drive shaft 4 is mount axially within the distal and proximal shaftprotectors 13.1, 13.2 and the pump housing 3.1 respectively. In the flowdirection 5 the drive shaft 4 has three sections: a distal section ofthe drive shaft 4.1 in the area of the body cap 10; a pump section ofthe drive shaft 4.2 on which the rotor 3.2 is non-rotatably mounted; anda proximal section of the drive shaft 4.3 extending from the pumpsection 3.1.3 to the clutch 9. The rotor 3.2 is adhesive-bonded to thedrive shaft. Other non-positive types of connection such as welding orclamping may however also be provided.

To guard against blood damage due to the rotation movement of the driveshaft 4 and adhesion of blood constituents to the drive shaft 4, theproximal shaft protector 13.2 (FIG. 2, FIG. 6) separates the proximalsection 4.3 of the drive shaft 4 physically from the pump medium. Thisprevents the build-up of shear forces. There is no direct interactionbetween the drive shaft 4 and the blood due to the very small gap, andonly minimal transport of blood through this gap is possible. The distaland proximal shaft protectors 13.1, 13.2 centre and support the driveshaft 4 in operation and during the compression and expansion process.

The drive shaft 4 is preferably formed by several, in particular six,wires (not shown) wound to left or right around a core. The outsidediameter of the drive shaft 4 is roughly 0.48 mm. The drive shaft 4 mayhowever also have a different number of cores and wires and a smaller orlarger diameter. The diameter of the drive shaft may lie in the rangebetween 0.3 mm and 1 mm, and is preferably around 0.4 mm to 0.6 mm. Thesmaller the diameter of the drive shaft, the greater the possible speed,since the smaller the diameter the greater is the speed at which theperiphery of the drive shaft moves relative to its environment. A highperipheral speed is problematic when the drive shaft comes into contactwith the environment. The catheter device is designed for speeds of morethan 20,000 rpm and up to 40,000 rpm. The diameter of the drive shaft 4is therefore made as small as possible, but thick enough to give itadequate strength.

Against the direction of winding of the drive shaft 4—in the presentembodiment it is wound to the left—is a guide spiral 14 with oppositewinding (here wound to the right) fitted axially around the distal andproximal sections of the drive shaft 4.1, 4.3. Its purpose is tominimise friction of the drive shaft 4, to avoid wall contact of thedrive shaft 4 with the proximal catheter body element 8.2, and toprevent kinking of the drive shaft 4 as a result of bending. Through theguide spiral 14, the drive shaft 4 is guided and fixed or stabilised(FIG. 10). The guide spiral 14 may be made of stainless steel and gluedto the shaft protector 13.1, 13.2. The guide spiral may also be providedin the form of a spring. The direction of winding of the guide spiral 14may also be the same as the direction of winding of the drive shaft 4.

The drive shaft 4 extends from the distal end of the distal shaftprotector 13.1 in the flow direction 5 behind the distal connection bush12.1 to the clutch 9.

In combination with the guide spiral 14, the proximal catheter bodyelement 8.2 provides a connection, constant in length and torsion,between the pump head 3 and the clutch 9.

Provided at the proximal end of the distal shaft protector 13.1 is abearing washer 15 (FIG. 6). The bearing washer 15 is provided with athrough bore 15.1. The diameter of the through bore 15.1 correspondsroughly to the outside diameter of the drive shaft 4. The bearing washer15 is fitted on to the drive shaft 4 in such a way that it holds theproximal end of the distal shaft protector 13.1, bounding it in the flowdirection 5.

The bearing washer 15 is made for example of stainless steel, Teflon ora ceramic or other suitable material. The bearing washer 15 is bonded tothe stationary shaft protector using cyanacrylate adhesive and istherefore able to absorb axial forces against the flow direction 5 (formeans of connection see above).

In the pump section 4.2 of the drive shaft 4, the spiral-shaped,expandable rotor 3.2 is mounted non-rotatably on the drive shaft 4.Provided as rotor 3.2 in the present embodiment is a two-blade,comb-shaped frame structure 3.2.1 of nitinol or another memory material,e.g. plastic (see above), which is coated or encompassed withfluid-tightness by a PU skin (FIG. 11a ). I.e. the covering in the formof the PU skin is stretched between the comb-like frame structure.Because of the structure of the rotor 3.2 as a coated frame structure3.2.1 of nitinol, it is possible to expand or compress the rotor 3.2.The PU skin has high elasticity so that it is not damaged duringcompression.

The frame structure 3.2.1 has a continuous screw-like or spiral-shapedouter boundary frame 3.2.2 with several rotor struts 3.2.3 connected tothe boundary frame 3.2.2 and running radially inwards (FIG. 12). Rings3.2.4 are formed at the free ends of the rotor struts 3.2.3. The driveshaft 4 extends through the rings 3.2.4 of the rotor struts 3.2.3.

Provided between every two adjacent rings 3.2.4 there is a spacer sleeve16. The distal end of the rotor 3.2 abuts the bearing washer 15 with adistal-end spacer sleeve 16. The end spacer sleeves 16 may also be inthe form of a special bearing spacer sleeve 16. In this way two of theframe structures 3.2.1 form a two-blade rotor 3.2.

The rotor 3.2 may also be made in one piece (FIG. 11b ) or have severalframe structures (FIG. 11a ). Each frame structure forms a rotor blade.FIGS. 11b and 12 show a frame structure 3.2.1 for a rotor 3.2 whichforms two rotor blades. If required, it is also possible for severalrotor blades and therefore several frame structures 3.2.1 to be fittedto a rotor 3.2. The frame structure may also take any other suitableform.

The distance between two adjacent rings 3.2.4 is less than thecorresponding section of the spiral-shaped boundary frame 3.2.2. Thegreater the difference between the distance between two rings 3.2.4 andthe corresponding section of the spiral-shaped boundary frame 3.2.2, thegreater the pitch of the rotor. The pitch of the rotor 3.2 may thus beset by the length of the spacer sleeves 16, and may be varied within arotor 3.2.

The pitch of the rotor 3.2 is determined by the length and number ofspacer sleeves 16 relative to the dimensioning of the continuousspiral-shaped outer boundary frame 3.2.2 between two rotor struts 3.2.3.The length of the spacer sleeves 16 may be standard for all positions,but may also be varied symmetrically or asymmetrically for eachposition. The complete freedom for configuration makes possible veryflexible design of the rotor 3.2, in turn permitting different pumpproperties for the rotor 3.2.

The rotor 3.2 has high dimensional stability combined with flexiblescope for configuration with minimum use of material (e.g. thin framestructure). Maximum stiffness and stability are obtained. Neverthelessthe combination of the frame structure and the covering, which furthersupports the properties of the frame structure through stabilisation,allows very strong compression. This leads to very good compressibilityand expandability of the rotor. Owing to the good surface formation ofthe PU skin on the mesh structure, very good matching of the housingstructure to the rotor structure is possible.

In the compressed state, the rotor 3.2 has approximately the insidediameter of the compressed pump housing 3.1. The outside diameter of thecompressed pump housing is roughly between 2 mm and 4 mm and preferablyaround 3.3 mm.

In the expanded state, the spiral-shaped outer boundary frame 3.2.2 ofthe rotor 3.2 is a very short distance away from the inner surface ofthe pump housing 3.1. The distance between the outer boundary frame3.2.2 and the inner surface of the pump housing 3.1 is roughly between0.01 mm and 0.5 mm. The smaller the distance between the frame structure3.2.1 and the inner surface of the pump housing 3.1, the greater thepump performance of the rotor 3.2.

At the distal-end spacer sleeve 16 of the rotor there is contact withthe bearing washer 15 fixed to the distal shaft protector 13.1 and thedistal-end spacer sleeve 16, both of which are fitted on to the driveshaft 4. Since the rotor 3.2 is set into a rotary motion by the driveshaft 4, the distal spacer sleeve 16 of the rotor 3.2 contacts thebearing washer 15 in the manner of a sliding bearing. In this way adistal rotor bearing 17 is formed (FIG. 6). The drive shaft 4 is heldalmost free from play by the through bore of the bearing washer 15. Onlysmall free spaces (not shown) remain, however, due to the design of thedrive shaft 4.

During positioning, on account of the flow of the pump medium, the rotor3.2 is loaded with an axial force against the flow direction 5. Thisforce is diverted via the distal-end spacer sleeve 16 on to the bearingwasher 15.

To lubricate the distal rotor bearing, blood or serum is sucked in viathe through bore 10.3 of the body cap 10, the open spaces between thedistal shaft protector 13.1 and the drive shaft 4, and the open spacebetween the drive shaft and the bearing washer 15. The suction effectoccurs due to the rotary movement of the drive shaft 4 and the rotor3.2.

At the proximal-end spacer sleeve 16 of the rotor 3.2, the drive shaft 4is similarly held by a proximal connection bush 12.2.

Located at roughly the proximal end of the pump section 3.1.3 of thepump housing is a tubular elastic outlet hose 18 (FIG. 1, FIG. 13). Theoutlet hose 18 is made of PU and has a length of approximately 70 mm, adiameter of around 10 mm and a wall thickness of roughly 0.01 mm to 0.1mm and preferably around 0.03 mm. The two ends of the outlet hose 18 aretapered, with a cylindrical section being provided at the proximalconical end of the outlet hose.

The distal tapering end of the outlet hose 18 makes a tight seal withthe PU covering of the pump section 3.1.3 of the pump housing 3.1. Thecylindrical proximal section is connected securely to the proximalcatheter body element 8.2. Both are joined together with a fluid-tightseal by means of dissolved PU.

Located at the proximal end of the outlet hose 18 are several radiallyconsecutive outlets 18.1. The outlets 18.1 may be oval in the flowdirection 5. It is however also possible to make the outlets circular,half-moon-shaped or with any other geometry in order to generatedifferent outflows. The outlets 18.1 agitate the blood passing out intothe aortic bulb. This prevents a laminar flow with a resultant water jetpumping effect on the coronary arteries.

The outlet hose 18 takes the pump volume of the pump from the leftventricle via the aortic valve into the aorta. Here the outlet hose 18acts like a non-return valve. If there is a positive pressure differencebetween the outlet hose 18 and the aorta, then the outlet hose 18 isopen to a greater or a lesser extent depending on the flow volumegenerated by the pump. With a nil or negative pressure difference, theoutlet hose 18 closes just like the aortic valve due to its highflexibility, and lies closely against the proximal catheter body element8.2. This flexibility leads to good sealing during through flow, againstthe vela of the aortic valve. Because of this, there is only minimalbackflow from the aorta into the left ventricle.

Located at the proximal end of the catheter body element 8.2 are theclutch 9 and the motor 7. The distance between the pump head 3 and theclutch 9 and the length of the proximal catheter body element 8.2respectively may vary according to the patient and are approximately 90to 150 cm.

The method of expanding the rotor 3.2 is described below.

Fitted over the catheter device 1 is a tubular cover hose 29, sodesigned as to encompass the compressed pump head 3 together with theproximal catheter body element 8.2. The cover hose 29 holds the pumphead 3 in its compressed state.

After the pump head 3 has been correctly positioned, the cover hose 29is withdrawn from the fixed catheter device 1 until the pump head 3 isfree. Due to the spring force of the elastic material, the pump housing3.1 and the rotor 3.2 unfold radially outwards. In other words, the meshstructure 3.1.6 of the pump housing 3.1 and the frame structure 3.2.1 ofthe rotor 3.2 expand until they have reached their preset diameter.Temperature effects of the memory material may also be utilised toassist in the expansion process.

To remove the catheter device 1, the cover hose 29 is pushed forward upto the body cap 10, causing the rotor 3.2 and the pump housing 3.1 to becompressed and drawn into the cover hose, after which the latter isextracted through the puncture point.

The clutch 9 and the motor 7 are explained below.

The clutch 9 is a magnetic clutch (FIG. 14, FIG. 15). The clutch 9 has aclutch housing 19 with a distal magnet unit 23.1. The clutch housing 19is connected to the proximal catheter body element 8.2, which forms acontinuous hollow space. The clutch housing 19 separates the proximalcatheter body element 8.2 hermetically from a motor assembly 30. Themotor assembly 30 has a proximal magnet unit 23.2. The proximal magnetunit 23.2 is connected non-positively to the motor 7. The distal magnetunit 23.1 is connected to the drive shaft 4 via a clutch element 22.

The distal magnet unit 23.1 and the proximal magnet unit 23.2 arecoupled non-rotatably to one another through magnetic forces. Anon-positive connection with non-contact rotational force transfer isensured by the two magnet units 23.1, 23.2.

From the distal to the proximal end, the clutch housing 19 has a distalcylindrical section 19.1, a conically expanding section 19.2, a secondcylindrical section 19.3 and a proximal cylindrical section 19.4. Theclutch housing is made e.g. of polymethylacrylate (PMMA) or anothermaterial which can be injection-moulded or machined.

Formed in the distal cylindrical section 19.1 is a through bore,positioned centrally in the axial direction. The through bore extendsthrough the whole of the clutch housing 19.

From the distal end of the distal cylindrical section 19.1, the throughbore narrows in three stages from a first catheter body mounting section19.5 to a second guide spiral mounting section 19.6 and to a third driveshaft passage section 19.7.

The bore diameter of the catheter body mounting section 19.5 is around1.9 mm, that of the guide spiral mounting section 19.6 approximately1.28 mm and that of the third bore section roughly 1.0 mm.

The proximal end of the proximal catheter body is located in andsecurely connected to the catheter body mounting section 19.5 of theclutch housing 19. The guide spiral 14 is mounted in the guide spiralmounting section 19.6.

The drive shaft 4 extends through the through bore of the drive shaftpassage section 19.7 of the distal cylindrical section 19.1 and of theconically widening section 19.1, 19.2. The drive shaft passage section19.7 widens in the conically widening section 19.2 into a fourth boresection 19.8.

At the start of the second cylindrical section 19.3, the fourth boresection merges into a hollow-cylindrical bearing section 19.9. Locatedin the distal end section of the bearing section 19.9 is an outer ringmagnet 20.1. The outer ring magnet 20.1 is fixed in the bore of thebearing section 19.9 by a press fit, and may also or alternatively befixed by adhesive bonding.

The bearing section 19.9 has a diameter of approximately 10 mm.

At the start of the proximal cylindrical section 19.4 of the clutchhousing 19, the bore of the bearing section 19.9 merges into a largersixth distal clutch section 19.10. Formed in the distal clutch section19.10 is a radially aligned rinsing bore 19.15.

Connected to the rinsing bore is a pump (not shown) for the introductionof a medium (e.g. NaCl, glucose solution, Ringer's solution, plasmaexpander, etc.).

The bore of the distal clutch section 19.10 merges into a largerproximal clutch section 19.11. Formed in the shoulder 19.12 between thedistal and proximal clutch sections 19.10, 19.11 are radiallysymmetrical 8×M 1.6 tapped holes 19.13. At the proximal end of theproximal section 19.4, three L-shaped recesses 19.14 are distributedaround the periphery.

The distal clutch section 19.10 has a diameter of approximately 22 mm.The rinsing bore 19.15 has a diameter of around 6.5 mm and the proximalclutch section 19.11 has a diameter of around 30 mm.

The proximal end of the drive shaft 4 is connected non-rotatably andsecure against tension and compression (non-positively) to a square rod21 (FIG. 17). In the axial direction the square rod 21 has a recess 21.1to accommodate the proximal end of the drive shaft 4. The drive shaft 4is fixed in the recess. The square rod 21 is made e.g. of brass, whichhas good lubrication properties. Other suitable materials are all thosewhich may be extruded or machined, such as e.g. PE, PP, PTFE, gold,silver, titanium, diamond, etc.

The square rod 21 has a length of around 19.4 mm and a cross-section ofapproximately 2.88 mm×2.88 mm.

The square rod 21 transmits the rotary motion of the motor to the driveshaft. The square rod 21 may have any desired geometrical form whichpermits a statically determined force application.

The square rod 21 is held by an axial recess 22.1 within arotation-symmetric clutch element 22, with the ability to slide axially(FIG. 23). By this means it is able to compensate for differences inlength in the axial direction (FIG. 18). The recess 22.1 is formed by alarger central bore and four smaller bores arranged along the peripheryof the central bore. The bores may be made by drilling, erosion,ultrasonic drilling, laser drilling or water jet drilling.

The arrangement of the bores provides four double stop edges runningaxially. The recess 22.1 is provided within a cylindrical section 22.2of the clutch element 22 and extends from the distal end of the clutchelement 22 until shortly before a disc-shaped proximal section 22.3 ofthe clutch element 22.

The cylindrical section 22.2 has an outside diameter of around 8 mm andthe disc-shaped proximal section 22.3 has an outside diameter ofapproximately 18 mm.

The recess 22.1 is made in such a way that the square rod 21 is heldfixed radially and in the peripheral direction, and able to slideaxially. The radial fixing of the square rod 21 is effected through thecontact of all four longitudinal edges of the square rod 21 with oneeach of the four double stop edges of the recess 22.1. Axial movement ofthe square rod 21 in the recess 22.1 results in only minimal friction atthe corresponding lines of contact.

It is also possible to provide more or less stop edges. Instead of asquare rod it is possible to provide e.g. a triangular or five-sided rodor a profiled rod with any desired cross-sectional surface remainingconstant in the longitudinal direction of the rod. The recess 22.1should be matched in shape to the cross-sectional surface of theprofiled rod.

At the distal end and at the periphery of the cylindrical section 22.2of the clutch element 22, a shoulder 22.4 is formed. Mounted on thisshoulder 22.4 is a second inner ring magnet 20.2. The shoulder 22.4accommodates the inner ring magnet 20.2 in such a way that its outersurface lies flush with the cylindrical surface of the cylindricalsection 22.2. This forms, in combination with the outer ring magnet 20.1similarly encompassing it in the bearing section 19.9 of the clutchhousing 19, a magnet ring bearing 20.3.

In the magnet ring bearing 20.3, the two ring magnets 20.1, 20.2 are soarranged that e.g. the north pole of the outer ring magnet is orientedtowards the distal end and the south pole towards the proximal end. Thenorth and south poles of the inner ring magnets are correspondinglyopposite one another. Similarly, the north and south poles of the tworing magnets could also be reversed. The magnet ring bearing 20.3centres the drive shaft 4 axially and radially. The radial centering iseffected through the radial attraction forces in the radial direction.The axial centering is effected by means of magnetic restoring forcesgenerated by a slight offset of the inner ring magnet 20.2, which pullthe inner ring magnet 20.2 into a position coinciding axially with theposition of the outer ring magnet 20.1. With a greater offset, however,repelling forces occur between the two magnet rings 20.1 and 20.2,causing them to be pressed apart.

In the magnet ring bearing 20.3 the ring magnets 20.1, 20.2 are not incontact, i.e. no lubrication is required. In addition, the magnet ringbearing acts as a vibration damper.

Formed in the disc-shaped section 22.3 of the magnetic clutch element 22at the proximal end of the clutch element is a magnet mounting 22.5. Themagnet mounting 22.5 is a centric circular recess.

The centric circular recess 22.5 has a diameter of approximately 16.5 mmand a depth of around 3 mm.

The magnet mounting 22.5 accommodates the annular distal magnet unit23.1 comprised of four segments. The annular distal magnet unit is gluedinto the magnet mounting 22.5.

Formed centrally in the proximal end face of the clutch element 22 is aball head bearing mount 22.6. The ball head bearing mount 22.6 is aroughly hemispherical recess 22.6.

The hemispherical recess 22.6 has a diameter of approximately 0.5 to 1.3mm.

The square rod 21 and the cylindrical section clutch element 22respectively are held by the fourth bore section 19.8 and the bearingsection 19.9 of the clutch housing 19. The disc-shaped section 22.3 ofthe clutch element 22 is held by the distal clutch section 19.10 of theclutch housing 19.

The clutch housing 19 is separated hermetically from the motor assemblyby a terminating disc 24 (FIG. 19). The clutch housing 19 has a gas- andfluid-tight seal apart from the rinsing bore 19.15 in the clutch element22 and the open spaces between the drive shaft passage section 19.7 andthe drive shaft 4.

The terminating disc 24 is mounted on the shoulder 19.12 of the clutchhousing 19 and is fixed by means of eight screws, suitably held by bores24.1 arranged with radial symmetry in the terminating disc 24, andscrewed into the tapped holes 19.13 of the clutch housing 19. Thisconnection is fluid- and gas-tight. The terminating disc 24 is made forexample of polymethylacrylate (PMMA) or another non-metallic material(e.g. PEEK, PEBAX, Teflon, PP, PE, all non-magnetic materials which canbe injection-moulded, extruded or machined).

On the distal side, the terminating disc 24 has a central thickersection 24.2. Formed in the centre of the terminating disc 24 is athrough bore 24.3 and a centric hemispherical recess 24.4. Fixed in thethrough bore 24.3 is a cylindrical centering pin 24.5 (FIG. 21). Mountedon the centering pin 24.5 is a ball head 24.6 which is held in thehemispherical recess (FIG. 15, FIG. 20).

The distal magnet unit 23.1 is biased by a force towards the proximal.These opposing forces produce a resultant force which presses the clutchelement 22 against the ball head 24.6. This resultant force is set sothat the ball head 24.6 is supported securely, while at the same timewear in the ball head bearing is kept to a minimum.

In combination with the distally located ball head bearing mount 22.7 ofthe clutch element 22, the ball head 24.6 forms a ball head bearing 25.The ball head bearing 25 is a sliding bearing. Other sliding bearings,such as e.g. a conical head bearing or a cylinder head bearing are alsopossible, with a cone or a cylinder provided as bearing body instead ofthe ball. The mounting is suitably matched to the shape of the bearingbody.

In conjunction with the magnet ring bearing 20.3, the ball head bearing25 provides axial centering and guidance, within the clutch housing 19,of the clutch element 22 and the drive shaft 4 mounted within it.

The axial centering of the magnet ring bearing 20.3 is effected byproviding that the inner ring magnet 20.2 is mounted axially not exactlyin the centre of the outer ring magnet 20.1, but slightly offset to theproximal side. By this means, the inner ring magnet 20.2 is biasedtowards the distal side. The ball head 24.6 may be made of ruby,aluminium oxide or a rigid plastic.

To prevent blood and serum from being sucked in through the open spacesbetween the drive shaft 4 and the proximal rotor bearing 17.2, due tothe rotary movement of the drive shaft 4, and the blood coagulatingand/or adhering to the drive shaft 4, a rinsing medium is introducedthrough the rinsing bore in the clutch housing to generate acounter-pressure to the sucked-in or pressed-in blood flow. By thismeans the ball head bearing is lubricated. Suitable rinsing agents aree.g.: 3-20% glucose solution, 5-40% dextrane solution with a molarweight of 5,000 to 65,000, in particular 10% dextrane solution, molarweight 40,000 in 0.9% NaCl, Ringer's solution: an electrolyte mixturesolution with K, Na, Mg, other physiological electrolyte solutions.

The motor assembly comprises the proximal magnet unit 23.2, a proximalmagnet mounting 26, a coupling flange 27, a motor mounting 7.1, with acooling fan mounted thereon and the motor 7 (FIG. 14, FIG. 22).

On the proximal side of the terminating disc 24, at a distance ofroughly 0.5 to 8 mm and preferably around 1 to 2 mm, there is a proximalmagnet unit 23.2 mounted axially flush with the distal magnet unit 23.1.Like the distal magnet unit 23.1, the proximal annular magnet unit 23.2has four segments.

The magnet mounting 26 is disc-shaped and has a centric circular recess26.1 on its distal side. Bonded into the recess 26.1 by means oftwo-component epoxy resin or cyanacrylate adhesives are, as in thedistal magnet unit 23.1 (see above), four magnet segments.

The four segments of the distal and proximal magnet units 23.1, 23.2 maybe in the form of bent bar magnets, each with different poles at theirend sections. The four segments may also be in the form of short axiallyaligned bar magnets, arranged in a ring. It is also possible to providemore than four segments. In the original position the two magnets arearranged so that in each case one north and one south pole of the barmagnets of the two magnet units 23.1, 23.2 overlap and attract oneanother.

The four segments are arranged four times with their north and southpoles alternating on impact, so that the segments attract one magneticunit. The distal and proximal magnet units 23.1, 23.2 are arrangedrelative to one another so that in each case complementary poles lieopposite one another. By this means the two magnet units attract oneanother and a torque is transmitted, since the magnetic forces wish tomaintain this complementary pole configuration.

The centric circular recess 26.1 has a diameter of around 16.5 mm and adepth of around 3 mm.

The magnet mounting 26 is connected to a motor shaft 7.2 of the motor 7.The magnet mounting 26 is mounted rotatably within a suitably formedrecess of the coupling flange 27 of the motor mounting. Provided alongthe outer periphery of the annular web of the recess are three dowelpins 27.1, evenly spaced.

The clutch housing 19 is connected to the dowel pins 27.1 of thecoupling flange 27 of the motor assembly via the L-shaped recesses 19.14of the clutch housing 19.

The coupling flange 27 is fastened to a distal end face 7.1.1 of themotor mounting, while maintaining axial symmetry. The motor mounting 7.1is a rectangular body with cooling fins 7.1.3 provided on its side faces7.1.2.

In the axial direction, the motor mounting 7.1 has a centrally locatedbore 7.1.4, through which the motor shaft 7.2 is guided. Also providedis an axially flush recess 7.1.5 in which the motor 7 is fitted.

The motor 7 is for example a standard electric motor from the companyFaulhaber with an output of 38 W at 30,000 rpm, or any other suitablemotor.

A cooling fan is provided on one side face 7.1.2 of the motor mounting7.1.

Provided over the pump head 3 and a distal section of the proximalcatheter body element is a cover hose 29. The cover hose 29 has aninside diameter which, in the area of the pump head 3, corresponds tothe outside diameter of the unexpanded pump housing. The outsidediameter of the cover hose is approximately 3 mm.

The method of coupling with the magnetic clutch 9 is now describedbelow.

The two magnet units 23.1, 23.2 are separated physically from oneanother by the terminating disc 24 in the clutch housing 19. Anon-positive connection is created by the magnetic attraction forcesbetween the two magnet units 23.1, 23.2. Here the respectively oppositepoles of the two magnet units 23.1, 23.2 are opposite one another, sothat they attract one another and a torque-resistant non-positiveconnection is formed.

Also by this means the ball head bearing mount 22.7 of the clutchelement 22 is pressed on to the ball head 24.6 of the terminating disc24 to form the ball head bearing 25. The ball head bearing centres theaxial course of the drive shaft 4.

Through the arrangement of the two ring magnets 20.1, 20.2 of the magnetring bearing 20.3, the inner ring magnet 20.1 is guided radially in theouter ring magnet 20.2 with constant clearance. In this way the magnetring bearing 20.3, in combination with the ball head bearing 25, centresand guides the rotation-symmetric motion of the clutch element 22 andthe drive shaft 4 respectively, in order to prevent any impact orimbalance.

Via the non-positive connection between the magnet units 23.1, 23.2, therotary motion transmitted by the motor 7 via the motor shaft 7.2 to theproximal magnet unit 23.2 is transferred to the distal magnet unit 23.1.

The motor shaft 7.2 rotates at a speed of around 20,000 rpm to 40,000rpm and preferably around 32,000 rpm to 35,000 rpm, which is transmittedto the drive shaft 4. At 32,000 rpm the rotor 3.2 has a pump performanceof approximately 2 l/min to 2.5 l/min at a differential pressure of 60mm Hg.

In the event of jamming of the rotor 3.2, the non-positive connectionbetween motor 7 and drive shaft 4 must be broken, to prevent“winding-up” of the drive shaft 4 while the rotor is stationary.“Winding-up” of the drive shaft 4 could lead to a change in position ofthe pump head 3, resulting in damage to the heart and/or the aorta andveins.

As soon as the rotor 3.2 jams, the drive shaft 4 twists and shortens,and the resistance at the distal magnet unit 23.1 increases. Themagnetic fields between the proximal and the distal magnet units 23.2,23.1 do not overlap completely in operation, since the distal magnetunit 23.1 always trails the proximal magnet unit 23.2 a little. If nowthe torque required at the distal magnet unit 23.1 increases, the northand south poles of the magnet units 23.1, 23.2 no longer overlap butinstead abut one another. By this, the distal magnet unit 23.1 ispressed away from the proximal magnet unit 23.2 in the distal direction.The magnetic connection between the two magnet units 23.1, 23.2 isbroken and the drive shaft 4 comes immediately to a stand.

Due to the displacement of the clutch element 22 in the distaldirection, the inner ring magnet 20.2 of the clutch element 22 issimilarly shifted in the distal direction and the north and south polesof the two ring magnets 20.1, 20.2 of the magnet ring bearing 20.3 nolonger overlap but instead abut one another. By this means, the clutch 9is held in the decoupled state, resulting in a lasting decoupling ofmotor 7 and drive shaft 4.

The amount of transferable torque is limited by the magnet ring bearing20.3 and the magnetic connection of the two magnet units 23.1, 23.2. Assoon as the set torque is exceeded, the two magnet units 23.1, 23.2separate. Owing to the rapid rotary motion, the distal magnet unit 23.1can no longer follow the proximal magnet unit 23.2, since the magneticbinding forces are no longer adequate. Because of this, the north andsouth poles no longer overlap and the magnet units 23.1, 23.2 repel oneanother. The connection of the magnet units 23.1, 23.2 is broken and themaximum transferable torque is limited. The magnet units 23.1, 23.2 areheld in the decoupled state by the magnet ring bearing 20.3 through themutual repulsion of the ring magnets 20.1, 20.2.

This state may be changed again by the application of an outer magneticfield. By means of a magnet guided past the clutch housing 19 fromdistal to proximal, the two magnet units 23.1, 23.2 may be brought backinto their coupled original position.

According to the invention the clutch housing 19 and the motor assembly30 are physically separated from one another. Because of this it ispossible to lubricate the drive shaft 4 through the pump located at therinsing bore 19.15, at around 5-10 ml/h, despite the high speed, therebyminimising friction. It may also be provided for an infusion to be madevia the rinsing bore 19.15, which similarly lubricates the drive shaft4.

The small diameter of the drive shaft is advantageous at high speeds ofaround 32,000 rpm. With greater diameters the peripheral speed would betoo high and the friction could lead to damage to the drive shaft 4 andthe adjacent components.

On account of the physical separation by the terminating disc 24 it ispossible to lubricate and/or seal the drive shaft 4. No known bearingthrough which a shaft is guided would remain leak-proof and allowtrouble-free running with this size and at such speeds.

The arrangement of the ball head bearing 25 (sliding bearing), themagnet ring bearing 20.3 (non-contact, damping and centering) and theaxial sliding bearing between the drive shaft 4 and the clutch housing19 creates three stabilisation points. This enables the drive shaft 4 totransmit a torque even if there is an axial change in length(lengthening and shortening). A change in length occurs, for example,when the pump head 3 is compressed. Here the rotor 3.2 is pressedtogether, folded around the drive shaft and clamped in place in thehousing. The pump housing 3.1 extends to the proximal side. The driveshaft 4 is able to move sufficiently for it not to be torn away from therotor 3.2. The ability of the drive shaft 4 to slide makes it possibleto compensate for change in length of the PU catheter body due totake-up of liquid, variations in temperature, and bending of theproximal catheter body element 8.2, which affects the lengthrelationships between drive shaft 4 and proximal catheter body element8.2. This mechanism is possible because of the ability of the square rod21 to slide within the axial recess 22.1.

The pump head 3 is located in the left-hand heart chamber in such a waythat the outlet hose 18 is arranged roughly centrally in the transitionfrom the aorta to the heart, i.e. in the area of the heart valve. Thecatheter device 1 is preferably designed so that a certain pump pressurein the range of around 100 mm Hg to 150 mmHg may be obtained from it. Ifthe heart is in the systole, then the catheter device pumps blood whenthe pressure built up by the heart is less than the pump pressure. Asick heart is thus relieved of stress. During the diastole, the pressuredifference is opposite. If the pressure difference is greater than thepump pressure, then the catheter device can not pump blood. In this casethe outlet hose is pressed together by the heart valve, so that it isclosed. If however the pressure difference is less than the pumppressure, then some blood will be pumped against the pressuredifference.

FIG. 24 shows the catheter device 1 positioned to give left-side supportto the heart. The pump head 3 is located completely in the left heartchamber. The outlet hose extends through the heart valve.

To insert the catheter device, firstly a cover hose 29 is guided by aguide wire into the left heart chamber (Seldinger technique). The guidewire is then removed from the cover hose. The catheter device 1 isinserted through the cover hose with compressed and cooled pump housing3.1 and rotor 3.2 until the catheter device 1 with the pump head 3 hasreached the left heart chamber. Unfolding takes place through thepulling back of the cover hose 29 on to the fixed catheter body 8, untilthe tip of the cover hose 29 has released the pump head 3.

To remove the system, the cover hose 29 is pushed forward up to the bodycap 10, causing the rotor 3.2 and pump housing 3.1 to be drawn into thecover hose 29 in the compressed state, after which the cover hose isextracted through the puncture point.

In a further embodiment of the present invention, provision is made fora pump medium to be pumped from proximal to distal, i.e. against theoriginal flow direction 5 (FIG. 25 II). To support the rotor 3.2 in theaxial direction and to absorb the bearing forces, the bearing washer 15is provided on the proximal side of the rotor 3.2. The flow direction tothe distal side may be obtained either by reversing the direction ofrotation from that of the embodiment above, or by inverting the pitch ofthe rotor 3.2. The outlet hose 18 is located at the distal end of thepump section of the clutch housing 19 and extends beyond the pump headin the distal direction. To reinforce the outlet hose 18 it may have amesh structure of a memory material e.g. similar to that of the pumphousing. The body cap 10 extends beyond the distal end of the outlethose.

In operation, the pump medium flows into the pump housing through thepump housing outlets now serving as inlets, and passes into the outlethose 18 through the pump housing inlet now serving as the outlet. Thepump medium passes out of the catheter device 1 through the distal endof the outlet hose.

The embodiment just described may be provided for example for use in theright ventricle.

In a further embodiment, the catheter device according to the inventionmay also be designed so that pumping from distal to proximal and fromproximal to distal is possible (FIG. 25 III).

In this embodiment, bearing washers 15 are provided at the distal andproximal ends of the rotor 3.2. The outlet hose 18 is located at thedistal end of the pump section 3.1.3 of the pump housing 3.1 and extendsin the distal direction. For reinforcement, the outlet hose 18 has amesh structure, e.g. similar to that of the pump housing. The meshstructure is covered by a PU skin. The diameter of the outlet hose 18corresponds roughly to that of the expanded pump housing.

In operation a pump medium may enter or exit through the outlets of thepump housing. The pump medium then passes for example via the outlets ofthe pump housing and the inlets of the pump housing into the outlethose, and exits at the distal end of the outlet hose. With the directionof pumping reversed, the flow through the catheter device iscorrespondingly reversed. This means that the pump medium enters theoutlet hose at the distal end of the outlet hose, and arrives at theoutlets of the pump housing via the inlets of the pump housing.Consequently, a flow to distal or proximal is possible through thepressure- and suction-stabilised outlet hose 18.

The embodiment just described may be used for example for drainage orfilling of hollow organs or spaces.

The reversed direction of flow may be obtained on the one hand byreversing the direction of rotation of the rotor and on the other handby inverting the pitch of the rotor.

The invention is described above with the aid of an embodiment in whichthe magnet units each have four bent bar magnets, each placed next toone another with opposite poles. Within the scope of the inventionhowever the magnet units may also be so designed that the north andsouth poles of the magnet units are oriented in the axial direction,wherein the poles are provided on the axial surfaces facing the distalor proximal end. The magnets are arranged in a ring as in the previousembodiments.

Through such an alignment of the north and south poles of the magnets,the two magnet units attract with greater magnetic forces. By this meansit is possible to transmit a higher torque via the clutch.

A clutch of this kind may be used for example to drive a milling headinstead of a rotor. Using such a micro-miller, e.g. kidney stone orbones may be milled with minimal invasion.

The number of magnets may in principle be varied as desired.

The radial compressibility of the components makes it possible torealise a very small puncture diameter, suitable for percutaneousimplantation by the Seldinger technique, on account of the very smalldiameter of the catheter device, amounting to approximately 3 mm. Duehowever to the expansion of the rotor up to a diameter of around 15 mm,it is still possible to obtain very high pump performance.

Known from the prior art are expandable catheter pumps (e.g. U.S. Pat.No. 4,753,221) which have a propeller with several rigid pump blades.These are mounted pivotably. Since the blades are rigid, they can not bemade as wide as desired since, in the folded state, they would require acatheter which was too thick. Pump performance is therefore limited.

The rotor according to WO 99/44651 has an elastic band for connecting anitinol filament to a rotation axis. Because of this elastic connection,the filament is not perfectly centred. During pumping, this can lead tovibrations which make higher speeds or rates of pumping impossible.

Because of the frame structure of the rotor with boundary frame androtor struts in accordance with the catheter device 1, the rotor is morestable, capable of folding and of expansion to virtually any diameterrequired. Due to the fact that the rotor may be virtually as long asdesired in the axial direction, the radial extent of the rotor may bechosen freely. This makes it possible to obtain virtually any level ofpump performance, in particular very high performance, and it ispossible to adapt pump performance specifically for each application.

The pitch of the rotor may also be varied as desired. The rotor may bedesigned with one or several rotor blades, with the rotor bladesaccordingly having a quarter, a half a whole or as many twists aroundthe drive shaft as desired. This means that the rotor may be varied asdesired in its size, shape and pitch, and may therefore be used for themost diverse applications.

LIST OF REFERENCE NUMBERS

-   1 catheter device-   2 distal end-   3 pump head-   3.1 pump housing-   3.1.1 distal connection section-   3.1.2 intake section-   3.1.3 pump section-   3.1.4 outlet section-   3.1.5 proximal connection section-   3.1.6 mesh structure-   3.1.7 apertures-   3.1.7.1 small rhombus-   3.1.7.2 large rhombus-   3.1.7.3 medium-sized rhombus-   3.1.8 PU covering of the pump housing-   3.2 rotor-   3.2.1 frame structure-   3.2.2 boundary frame-   3.2.3 rotor struts-   3.2.4 rings-   4 drive shaft-   4.1 distal section of the drive shaft-   4.2 pump section of the drive shaft-   4.3 proximal section of the drive shaft-   5 flow direction-   6 proximal end-   7 motor-   7.1 motor mounting-   7.1.1 end face-   7.1.2 side face-   7.1.3 cooling fins-   7.1.4 bore-   7.1.5 recess-   7.2 motor shaft-   8 catheter body-   8.1 distal catheter body element-   8.2 proximal catheter body element-   9 clutch-   10 body cap-   10.1 ball-   10.2 cylindrical section-   10.3 through bore-   10.4 axial bore-   10.5 step-   12.1 distal connection bush-   12.2 proximal connection bush-   13.1 distal shaft protector-   13.2 proximal shaft protector-   14 guide spiral-   15 bearing washer-   15.1 through bore-   16 spacer sleeves-   17 distal rotor bearing-   18 outlet hose-   18.1 outlet-   19 clutch housing-   19.1 distal cylindrical section-   19.2 conically widening section-   19.3 second cylindrical section-   19.4 proximal cylindrical section-   19.5 catheter body mounting section-   19.6 guide spiral mounting section-   19.7 drive shaft passage section-   19.8 fourth bore section-   19.9 bearing section-   19.10 distal clutch section-   19.11 proximal clutch section-   19.12 shoulder-   19.13 tapped hole-   19.14 L-shaped recess-   19.15 rinsing bore-   20.1 outer ring magnet-   20.2 inner ring magnet-   20.3 magnet ring bearing-   21 square rod-   21.1 recess-   22 clutch element-   22.1 recess-   22.2 cylindrical section-   22.3 disc-shaped section-   22.4 shoulder-   22.5 magnet mounting-   22.6 ball head bearing mount-   23.1 distal magnet unit-   23.2 proximal magnet unit-   24 terminating disc-   24.1 bores-   24.2 thicker sections-   24.3 through bore-   24.4 hemispherical recess-   24.5 centering pin-   24.6 ball head-   25 ball head bearing-   26 magnet mounting-   26.1 recess-   27 coupling flange-   27.1 dowel pins-   28-   29 cover hose-   30 motor assembly

That which is claimed is:
 1. A catheter device comprising a drive shaftconnected at a proximal end to a motor; a rotor mounted on a distal endsection of the drive shaft; a pump housing which encompasses the rotor,wherein the pump housing has at least one aperture for the dischargingof a pump medium into a flexible outlet hose extending from the pumphousing; wherein at least a portion of the pump housing is surrounded bythe outlet hose, and the pump housing extends distally from the outlethose; and wherein a first end and a second end of the outlet hose areboth tapered.
 2. The catheter device according to claim 1, wherein acatheter body extends through the outlet hose in which the drive shaftis disposed.
 3. The catheter device according to claim 1, wherein asection of the outlet hose apart from the pump housing is fixed to thecatheter body in which the drive shaft is disposed.
 4. The catheterdevice according to claim 1, wherein the outlet hose is elastic ortubular.
 5. The catheter device according to claim 1, wherein the pumphousing is formed by a mesh structure comprising apertures wherein theapertures are closed in at least one section of the pump housing by anelastic covering.
 6. The catheter device according to claim 5, whereinthe mesh structure of the pump housing is made from a memory material.7. The catheter device according to claim 6, wherein the memory materialis nitinol.
 8. The catheter device of claim 6, wherein the memorymaterial is one of plastic, ferrous alloy, and copper alloy.
 9. Thecatheter device according to claim 5, wherein the elastic covering ofthe pump housing is in the form of a polymer coating such as PU, PE, PP,silicone or parylene.
 10. The catheter device according to claim 5,wherein the pump housing has a distal connection section, a conicalintake section, a pump section, a conical outlet section and a proximalconnection section.
 11. The catheter device according to claim 10,wherein the mesh has larger apertures in the conical intake section andthe conical outlet section than in the pump section.
 12. The catheterdevice according to claim 1, wherein the outlet hose at a proximalsection has a plurality of radially consecutive outlets wherein theoutlets are shaped as one of oval, circular, and halfmoon-shaped, andwherein blood passing through the outlets is agitated by a shape of theoutlets.
 13. The catheter device according to claim 1, wherein acylindrical section is disposed at a front end in flow direction of theoutlet hose and the cylindrical section is fixed to a catheter bodyelement.
 14. The catheter device according to claim 1, wherein theoutlet hose is made from polyurethane (PU).
 15. The catheter deviceaccording to claim 1, wherein the outlet hose has a length of about 70mm, a diameter of about 10 mm and a wall thickness of about 0.01 mm to0.1 mm and preferably about 0.03 mm.
 16. The catheter device of claim 1,wherein the pump housing is configured to allow fluid flow from the pumphousing through the at least one aperture into the outlet hose.
 17. Thecatheter device of claim 1, wherein the outlet hose is configured to becompressed in a middle section to act as a non-return valve.
 18. Thecatheter device of claim 17, wherein the outlet hose is configured to bepositioned across an aortic valve, and wherein the outlet hose isconfigured to be compressed by the aortic valve.